Renal artery stenting conferred no added benefit to medical management for the treatment of patients with atherosclerotic renovascular disease in a large, randomized clinical trial.

Findings from the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial confirmed that stenting with aggressive hypertension and lipid lowering drug treatment was no better than drug treatment alone for preventing death from cardiovascular or renal causes or preventing complications such as heart attack, stroke, or progression of renal failure.

"Renal artery stenting remains a common procedure in current clinical practice," Christopher J. Cooper, MD, of the University of Toledo in Toledo, Ohio, and colleagues, wrote in NEJM. "The CORAL study shows that, when added to a background of high-quality medical therapy, contemporary renal artery stenting provides no incremental benefit. From this result, it is clear that medical therapy without stenting is the preferred management strategy for the majority of people with atherosclerotic renal artery stenosis."

Renal artery stenosis often occurs in combination with peripheral arterial or coronary artery disease, and its prevalence among the elderly has been reported to be as high as 7%.

Renal artery angioplasty has been suggested to reduce hypertension, a common complication of renal artery stenosis, in several uncontrolled trials, but this benefit was not seen in several randomized studies, the researchers reported.

Likewise, two randomized studies published in 2009 -- the ASTRAL trial and the STAR trial -- failed to show a clear benefit for renal artery stenting with respect to kidney function.

The newly published study is one of the largest randomized trials ever to assess the impact of renal artery stenting in patients with moderately severe obstructive renovascular disease, with the incidence of important cardiovascular and renal adverse events its major endpoints.

The trial included 947 patients with atherosclerotic renal artery stenosis and either systolic hypertension while taking two or more antihypertensive drugs or chronic kidney disease.

Unless otherwise contraindicated, medical therapy included the angiotensin II type-1 receptor blocker candesartan with or without hydrochlorothiazide, and the combination agent amlodipine-atorvastatin (Caduet), with the dose adjusted on the basis of blood pressure and lipid status.

Target blood pressure was less than 140/90 mm Hg in patients without coexisting conditions and less than 130/80 mm Hg in patients with diabetes or chronic kidney disease. Medications were adjusted until the blood pressure goal was reached.

Over a median follow-up period of 43 months (interquartile range, 31 to 55 months), the rate of the primary composite end point did not differ significantly between study participants who underwent stenting in addition to receiving medical therapy and those who received medical therapy alone (35.1% and 35.8%, respectively; HR with stenting, 0.94 (95% CI 0.76-1.17; P=0.58).

The researchers found no significant differences between the treatment groups in the rates of the individual components of the primary endpoint or in all-cause mortality.

There was a consistent, modest difference in systolic blood pressure favoring the stent group during the follow up (−2.3 mm Hg; 95% CI −4.4 to-minus 0.2; P=0.03), but the researchers noted that this did not translate into a reduction in clinical events.

Cooper and colleagues noted that a key issue in the interpretation of their results is whether the medical therapy given to the CORAL participants can be easily replicated in the clinical practice setting.

"The medical therapy in our study included the use of an angiotensin-receptor blocker, with or without a thiazide-type diuretic, with the addition of amlodipine for blood-pressure control," they wrote. "In addition, participants received anti-platelet therapy and atorvastatin for management of lipid levels, and diabetes was managed according to clinical practice guidelines."

They concluded that this regimen provided " remarkably good cardiovascular and renal outcomes" despite the advanced age and comorbidities of the study participants.

Editorial: Study 'Definitive Test'

In an editorial published with the study, interventional cardiologist John A. Bittl, MD, of Munroe Regional Medical Center in Ocala, Florida, wrote that the CORAL trial addressed a common criticism of the earlier randomized trials -- that they enrolled patients whose blockages were not severe enough to benefit from stenting.

"The current study required patients to have a stenosis of at least 60% of the diameter of a renal artery, which is a more stringent criterion than the threshold of 40% used in the ASTRAL and STAR trials, and yet it failed to show a clinical benefit of renal artery stenting," he wrote.

He added that in a subgroup analysis , there was no heterogeneity of the effect of stenting in patients with a stenosis of at least 80%, suggesting that even in patients with the most severe disease, the benefits of the procedure are difficult to predict.

Bittl concluded that the CORAL trial represents "a definitive test" of the usefulness of renal artery stents for moderately severe atherosclerotic disease that sends a clear message to patient and physicians.

"Until new treatments are found to be safe and effective, patients in everyday practice who have moderately severe atherosclerotic renovascular disease and either hypertension or stage 3 chronic kidney disease should receive medical therapy to control blood pressure and prevent the progression of atherosclerosis, but should not be corralled into getting a renal artery stent," he wrote.

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